ArticlePDF Available

Late Pleistocene (Rancholabrean) Glyptodont and Pampathere (Xenarthra, Cingulata) from Sonora, Mexico

  • The Mammoth Site
  • BLM - The Bureau of Land Management Lakewood Colorado (Retired)

Abstract and Figures

Los yacimientos ricos en fósiles de Térapa (área centro-oriental de Sonora) contienen más de 60 taxon zoológicas, muchos con afinidades tropicales como Crocodylus (crocodrilo), Hydrochaeris (capibara), y muchas aves. Los depósitos contienen además la dermis ósea de oído (osteodermis) de dos xenartros extintos, un gliptodonte (Glyptotherium cylindricum) y un armadillo gigante (Pampatherium cf. mexicanum) (Mammalia, Xenarthra). También se han hallado restos de gliptodonte en otras localidades de Sonora menos estudiadas. Las faunas de estas localidades contienen además el género Bison, lo cual indica que los depósitos son del Rancholabreano (Rancholabrean Land Mammal Age), Pleistoceno tardío. La presencia de Pampatherium en Térapa y de Glyptotherium en Térapa y los sitios del Río Mayo/Río Yaqui representa el primer recuento publicado de estas especies en Sonora y extiende grandemente su distribución conocida durante el Rancholabreano, o pleistoceno tardío, en unos 1,100 kms hacia el noroeste de México.
Content may be subject to copyright.
Late Pleistocene Glyptodont and Pampathere from Sonora, Mexico 439
Late Pleistocene (Rancholabrean) Glyptodont and Pampathere
(Xenarthra, Cingulata) from Sonora, Mexico
Jim I. Mead1,2,*, Sandra L. Swift1, Richard S. White3,
H. Greg McDonald4, and Arturo Baez5
1 Laboratory of Quaternary Paleontology, Quaternary Sciences Program, Northern Arizona University, Flagstaff, AZ 86001 USA.
2 Department of Geology, Northern Arizona University, Flagstaff, AZ 86001 USA.
3 International Wildlife Museum, 4800 W Gates Pass Road, Tucson, AZ 85745 USA.
4 National Park Service, 1201 Oakridge Dr. 250, Fort Collins, CO, 80525 USA.
5 College of Agriculture and Life Sciences, University of Arizona, Tucson, AZ 85721 USA.
The fossil-rich deposits of Térapa (east-central Sonora) contain more than 60 zoological taxa,
many with tropical af nities such as Crocodylus (crocodylian), Hydrochaeris (capybara), and many
birds. The deposits also contain the dermal ossicles (osteoderms) of two extinct xenarthrans, a glyptodont
(Glyptotherium cylindricum) and a pampathere (giant armadillo; Pampatherium cf. mexicanum).
Glyptodont remains are also known from other less-well studied localities in Sonora. The faunas from
these localities also contain the genus Bison, which indicates that the deposits are of the Rancholabrean
Land Mammal Age, late Pleistocene. The presence of Pampatherium at Térapa and the presence of
Glyptotherium at Térapa and the Río Mayo/Río Yaqui sites represent the rst published accounts of these
species from Sonora, and greatly extends their known geographical distribution during the Rancholabrean
by about 1,100 km into northwestern Mexico.
Key words: Xenarthra, pampathere, glyptodont, Rancholabrean, Pleistocene, Sonora, Mexico.
Los yacimientos ricos en fósiles de Térapa (área centro-oriental de Sonora) contienen más de
60 taxon zoológicas, muchos con a nidades tropicales como Crocodylus (crocodrilo), Hydrochaeris
(capibara), y muchas aves. Los depósitos contienen además la dermis ósea de oído (osteodermis) de dos
xenartros extintos, un gliptodonte (Glyptotherium cylindricum) y un armadillo gigante (Pampatherium cf.
mexicanum) (Mammalia, Xenarthra). También se han hallado restos de gliptodonte en otras localidades
de Sonora menos estudiadas. Las faunas de estas localidades contienen además el género Bison, lo cual
indica que los depósitos son del Rancholabreano (Rancholabrean Land Mammal Age), Pleistoceno tardío.
La presencia de Pampatherium en Térapa y de Glyptotherium en Térapa y los sitios del Río Mayo/Río
Yaqui representa el primer recuento publicado de estas especies en Sonora y extiende grandemente su
distribución conocida durante el Rancholabreano, o pleistoceno tardío, en unos 1,100 kms hacia el
noroeste de México.
Palabras clave: Xenartra, pampaterio, gliptodonte, Rancholabreano, Pleistoceno, Sonora, México.
Revista Mexicana de Ciencias Geológicas, v. 24, núm. 3, 2007, p. 439-449
Mead et al.
Members of the mammalian order Xenarthra comprise
a prominent part of the South American fauna. Most of the
evolutionary history of the group occurred on that continent,
yet by the late Miocene some members dispersed over the
emerging Panamanian land bridge of Central America to
populate Mexico, the United States, and portions of Canada
(Webb and Rancy, 1996). This dispersal was part of the
Great American Biotic Interchange (GABI) of Neotropical
and Nearctic taxa. As recorded in the North American fos-
sil record, it occurred primarily during the latest Miocene
(early Hemphillian Land Mammal Age (LMA); 9-7 Ma)
and continued intermittently through the late Pliocene to
early Pleistocene (late Blancan LMA and early Irvingtonian
LMA; 2.7-1.0 Ma) (Morgan, 2005).
Living and extinct members of each of the two sub-
orders of xenarthrans, the pilosans (sloths and anteaters)
and cingulates (armadillos, pampatheres, and glyptodonts)
(McDonald, 2002) are known from Mexico. Representatives
of these suborders dispersed during the GABI. Knowledge
about the evolutionary history and distribution of these taxa
has been based primarily on fossils from the United States.
The records of fossil xenarthrans in Mexico are less exten-
sive and inadequately understood as compared to those in
the United States, and the review of xenarthran fossils by
McDonald (2002) clearly illustrated a latitudinal bias to the
known distribution. This is unfortunate as the geographic
position of Mexico represents today the northern extension
of the Neotropics and the southern extension of the temper-
ate climates and biotic communities of the Nearctic. The
northern state of Sonora represents this critical boundary
between the two biomes, a zone that shifted north and south
with the pulsating changes of glacial and interglacial climate
changes during the Pleistocene.
Although many xenarthrans were present in North
America during the Neogene, some apparently were re-
stricted to the environments of Mexico and did not venture
into the temperate United States. The record of xenarthrans
from Mexico is intriguing yet clearly insuf ciently studied
to permit adequate statements about distribution patterns and
dispersal routes relative to chronology and environmental
change. Any evidence, especially from the northern portion
of Mexico, is signi cant and of biogeographic and envi-
ronmental importance. Of interest here are the cingulates,
which include three subgroups: Dasypodidae (living and
extinct armadillos), Pampatheriidae (extinct pampatheres or
giant armadillos), and Glyptodontidae (extinct glyptodonts).
The earliest record of cingulates in Mexico is from early
Blancan deposits in the state of Guanajuato. Pampatheres
are represented there by the genus Plaina in deposits
dated between 4.7 and 4.8 Ma, and for the glyptodonts by
Glyptotherium from layers dated between 3.9 and 3.1 Ma
(Flynn et al., 2005). Here we report remains of glyptodonts
and pampatheres from the deposits at Térapa in east-central
Sonora and other less studied localities within the state.
Today the only xenarthran to inhabit Sonora is the nine-
banded armadillo (Dasypus novemcinctus, Dasypodidae),
which lives in southern-most portion of the state at Alamos
(Mendoza-Durán, 2005).
The fossil-rich deposits of Térapa contain more than
60 zoological taxa, many with tropical af nities such as
Crocodylus (crocodylian) and Hydrochaeris (capybara),
along with many birds and Bison (bison) (Mead et al.,
2006). Carranza-Castañeda and Roldán-Quintana (2007)
brie y mention their recovery of surface nds of Bison
and Equus (horse) from Térapa. Térapa is located along the
Río Moctezuma in interior east-central Sonora (Figure 1;
29º 41’ N latitude; 109º 39’ W longitude, 605 m elevation).
The Río Moctezuma joins the Río Yaqui and enters the
Gulf of California (28ºN, 111ºW), positioning Térapa 350
km inland. The geological context and stratigraphy of the
deposits at Térapa are described in Mead et al. (2006). A lava
ow within the Moctezuma volcanic eld described by Paz-
Moreno et al. (2003) created at least one catchment basin
approximately 1 by 2 km adjacent to the Río Moctezuma.
Bison teeth and post-cranial remains recovered by Mead et
al. (2006) from throughout the 11 m of strati ed sediments
prescribe an assignment for the deposit and encased fauna
to the Rancholabrean (RLB) LMA of the late Pleistocene
(see Bell et al., 2004).
All fossil specimens from Térapa are temporarily
archived into the Laboratory of Quaternary Paleontology,
Quaternary Sciences Program, Northern Arizona University
(NAU QSP), Flagstaff, Arizona, USA. Within this system,
all specimens are curated into a numbering classi cation
specifically for Térapa (TERA) and eventually will be
returned to Sonora.
The cingulate remains from Térapa come from the
lowest As1/As2 sediments that represent the initial lling of
the basin and from the lower (Bp1) and upper (Bp2) marsh
units (Mead et al., 2006). Although it is not yet understood
how much time it took to ll the basin with 11 meters of
sediments and fossils, it is apparent that cingulates utilized
the local environments throughout the depositional history
of the catchment.
Río Mayo / Río Yaqui Localities
Howard Scott Gentry traveled extensively throughout
northwestern Mexico in the 1930s where he recorded fossil
deposits, as well as the modern vegetation. Although his
contributions about the vegetation are well published (see
references in Martin et al., 1998), his fossil discoveries are
less well known, mostly unpublished, and documented by
Late Pleistocene Glyptodont and Pampathere from Sonora, Mexico 441
May 10th, 1936, based on his plant collecting notes in the
Herbarium at the University of Arizona. La Botana is located
at approximately 490 m altitude and is about 10 km. west of
the town of Tesopaco. (Figure 1). The site is located close to
the divide between the Río Yaqui and Río Mayo drainages,
which are not clearly delineated on available maps. Gentry,
in a letter to the Frick Lab, also indicates that it is in the Río
Yaqui drainage. Martin et al. (1998) also thought that the
site was likely in the Río Yaqui drainage
Fossils were abundant and included Glyptotherium
in association with Bison, which indicates a RLB age for
the deposits. Gentry also recovered Equus, Camelops,
Mammuthus, and Odocoileus. Fossils were removed from
an ‘argillaceous lime’ unit. Brief site descriptions and a
map of collecting localities are recorded in Gentry’s eld
notes submitted to C. Frick, June 1, 1937. The locality was
visited on March 23, 1975 by Paul S. Martin and one of
his students, Geoff Spaulding (both then at the University
of Arizona, Desert Laboratory, Tumamoc Hill, Tucson,
Arizona). They made a small collection of vertebrate fos-
sils (Martin, pers. com.). Fossil recovered by the UA party
include the Glyptotherium osteoderms documented below,
and Equus, Bison, and cf. Capromeryx. Specimens from
La Botana are curated at NAU QSP (via the University of
eld notes and letters to Childs Frick (Gentry and Hadley,
1995:237-243). These letters and notes are archived in the
Department of Paleontology, American Museum of Natural
History (AMNH), New York. The materials collected by
Gentry in Sonora are preserved in the vertebrate paleon-
tology collections at the AMNH. We have examined these
brie y, but have not produced a detailed analysis. Only
those localities with remains of cingulates are presented
here. Clearly, additional studies of these fossil localities
are greatly desired; we plan further study of Gentry’s
Rancholabrean material from Sonora.
La Botana
Gentry described three localities from the vicinity
of Tesopaco: 1) 8 km southeast, 2) 16 km west and north,
and 3) 25 km west and north. Gentry’s eld notes for his
rst few weeks in this area are confusing. It appears likely
that his Tesopaco Locality 1 is what he later called Los
Coyotes, that Tesopaco Locality 2 is probably La Botana,
and that Tesopaco Locality 3 is Llano Prieto (the latter two
are described below).
Gentry rst visited La Botana between May 5th and
Figure 1. Map of Mexico and adjacent USA showing distribution of Glyptotherium (open square) from Gillette and Ray (1981) and McDonald (2002) and
Pampatherium (dot) from McDonald (2002) in relationship to the locations of Térapa, the Río Mayo/ Río Yaqui deposits, and La Brisca (open triangle)
from Van Devender et al., (1985). More detailed discussion about locations can be found in the text and in Mead et al. (2006).
Mead et al.
Arizona, Laboratory of Paleontology, Tucson) and in the
collections at the AMNH.
Llano Prieto
The Llano Prieto fossil locality is located north of La
Botana, up the headwaters of the Río Cedros, a tributary of
the Río Mayo. As noted below, Llano Prieto was originally
referred to as Tesopaco 3 by Gentry. An ‘argillaceous lime
and gravel’ unit with fossils is located about 6 m below
surface. Bison and an unveri ed record of Glyptotherium
were recovered together from the locality, and indicate a
RLB age for the remains. Data is recorded in H. S. Gentry’s
eld notes submitted to C. Frick, June 1, 1937. We have not
been able to locate a specimen of Glyptotherium from this
locality in the AMNH collections.
The site of Chinobampo is located along the Arroyo
Chinobampo, which appears to drain northwards into the
Río Mayo, and is about midway between Navajoa and
Alamos. The settlement of Chinobampo is shown on the
Mexican Topographic Map (1:50,000) Masiaca G12B56.
Some older maps show a ranch named ‘Agua China’ in
the same area. According to Gentry, ‘Chinobampo’ means
‘Chinaman Well’. Since the word “chino” locally also
means the tree palo chino (Havardia mexicana), Martin
et al. (1998) translate the place name as “Chino in the wa-
ter”. The site was mentioned brie y in Aveleyra Arroyo de
Anda (1964) and is notable for having produced a human
skull and some fragmentary postcranial remains, possibly
from the same layers that produced the Rancholabrean
fossil mammals. Gentry discovered the site January 10,
1937 (based on both a geological report written by John
C. Blick (another one of Frick’s collectors) and submitted
to Frick December 13, 1937, and Gentry’s plant collecting
notes in the Herbarium at the University of Arizona. Blick
and Gentry returned to Chinobampo in March of 1937 at
Frick’s request to make an intensive examination of the
geology. The geologic situation at Chinobampo appears
to be very similar to that described for Tèrapa, Sonora,
by Mead et al. (2006). A basalt ow dammed the arroyo,
causing an impoundment in which sediments consisting of
‘argillaceous lime, lime, and black lime’ were deposited.
Blick lists the following fossils in his notes: a palate of a
large species of Camelops, a horse skull (Equus), and the
partial skeleton of a Canis sp. (wolf). The ‘wolf’ skeleton is
listed in the Frick Laboratory receiving notes as ‘cat.’ The
same receiving notes list a Bison sp. mandible fragment and
four glyptodont osteoderms. A RLB age is assigned based on
the recovery of Bison with extinct species. Specimens from
Chinobampo are curated in the Department of Paleontology,
Order Xenarthra Cope, 1889
Suborder Cingulata Illiger, 1811
Superfamily Glyptodontoidea Gray, 1869
Family Glyptodontidae Gray, 1869
Genus Glyptotherium Osborn, 1903
Glyptotherium cylindricum (Brown) Gillette and
Ray, 1981
Fossil material. Osteoderms (dermal ossicles) assigned
to Glyptotherium cylindricum include:
Térapa— TERA-25, 27-30, 50: interior carapace
osteoderms; TERA-24, 49: lateral osteoderms near border;
TERA-26, 31: caudal border carapace osteoderm; TERA-
32-36, 45-48: conical osteoderms; TERA-37-44: anterior
osteoderm of caudal ring: TERA-51: large section of cara-
pace from single individual.
La Botana— NAU QSP-17887: one mid-carapace
osteoderm; NAU QSP-17886: one lateral border osteoderm;
AMNH 59592 and 59693: 163 isolated and 6 articulated
osteoderms; AMNH 59594: two mid-carapace osteoderms;
AMNH 96369: one mid-carapace osteoderm.
Llano Prieto— Mentioned in eld notes; no osteo-
derms were observed in the AMNH collections.
Chinobampo— Four mid-carapace osteoderms:
AMNH 59595. Only the ventral side of these osteoderms
is preserved. The dorsal side is obscured with a thick coating
of caliche-like carbonate.
Remarks and identi cation. North American glyptodonts
are distinct from the South American forms and placed in
their own genus Glyptotherium, which is closely related to
the South American genus Glyptodon (Gillette and Ray,
1981). The earliest glyptodont in Mexico, Glyptotherium
sp., is recorded from early Blancan deposits in central
Mexico (Carranza-Castañeda and Miller, 2004). There are
three recognized species of Glyptotherium from Mexico:
G. cylindricum [Rancholabrean LMA; one locality], G.
oridanum [Rancholabrean LMA; two localities], and G.
mexicanum [Rancholabrean LMA; one locality] (Gillette
and Ray, 1981; McDonald, 2002). Additional species are
described and are restricted to the United States and older
deposits (G. arizonae [Irvingtonian LMA] and G. texanum
[Blancan LMA]).
The distribution of the genus was more extensive
during the Blancan and Irvingtonian with remains occur-
ring in Arizona and New Mexico respectively (Morgan and
Lucas, 2005; Morgan and White, 2005; White and Morgan,
2005), and even north into Oklahoma (Czaplewski, 2004).
Records of late Pleistocene, RLB, Glyptotherium in the
United States are concentrated along the Gulf States region
(Gillette and Ray, 1981). Consequently from the Blancan to
the Rancholabrean there was a reduction in the range of the
genus to the east and south in the United States. Extensive
Late Pleistocene Glyptodont and Pampathere from Sonora, Mexico 443
eld studies have shown that no Rancholabrean records of
Glyptotherium exist in the Southwest United States (Mead
et al., 2005; Morgan and Lucas, 2005). Until now its distri-
bution in Mexico during the Rancholabrean was thought to
be restricted to central and southern portions of the country
(McDonald, 2002; Figure 1).
The dermal armor of glyptodonts is their single most
outstanding characteristic. Consequently the morphology of
the osteoderms has long been recognized as taxonomically
important. Each osteoderm that covers the body region
(carapace) is polygonal (six- or four-sided) and is tightly
sutured to its neighbors, inhibiting trunk mobility. For
a discussion of the development of the osteoderms, see
Holmes and Simpson (1931) and Hill (2006). The typical
hexagonal osteoderm has a central figure and several
peripheral figures symmetrically arranged around the
center, producing a characteristic and diagnostic rosette
pattern (terminology of Hill, 2006). Identi cation characters
used here follow Gillette and Ray (1981). In G. texanum,
the central figure is larger than the peripherals, and is
convex and slightly raised above the level of the attened
peripheral gures. In G. arizonae and G. cylindricum, the
central gures are relatively smaller than the peripherals,
not greater than 50 percent of the entire osteoderm diameter,
and are generally at to weakly convex. In G. oridanum
the central gure is approximately equal in size to those of
the peripherals, and is typically raised and weakly concave.
The central gure on the osteoderms of G. mexicanum is
generally large, never smaller than half (50 percent) of the
osteoderm diameter.
Although seemingly distinct for all the species, we
recognize that there is variation of the rosette size and pat-
tern within and among species. Isolate osteoderms may be
dif cult to accurately identify in all cases. Complicating
this is the fact that G. cylindricum and G. mexicanum are
less than adequately understood, being known only from
the type localities (Carranza-Castañeda and Miller, 1987;
McDonald, 2002). Better material may show that these
two taxa are synonomous. Until more complete carapaces
of Glyptotherium from Mexico are studied in detail and
apomorphies established for the osteoderms, we identify
our specimens from Sonora using the characters outlined
above from Gillette and Ray (1981). In addition, we omit
G. arizonae and G. texanum from consideration of the
Rancholabrean glyptodonts based on their earlier age as-
signment. Clearly much remains to be understood about
Mexican glyptodonts.
TERA-24 measures 39.6 by 34.8 mm. The thickness
varies from 11.2 to 12.6 mm which indicates that the os-
teoderm is from a lateral, near-border location (Figure 2a).
Due to location on the carapace, the TERA-24 specimen
does not have the typical rosette pattern.
TERA-25 is a typical rosette osteoderm of the mid-
carapace (Figure 2b). Overall the osteoderm measures 37.4
by 45.1 mm, and is 16.3 mm in thickness. The central gure
of the rosette measures 16.6 mm (36 percent of the greatest
diameter). The central gure is at and only slightly larger
than the peripheral gures, consistent with the pattern found
on G. arizonae and G. cylindricum (Gillette and Ray, 1981).
The above character would imply that the Glyptotherium
from Térapa is more similar to G. cylindricum than to G.
mexicanum. We use this solitary character to identify the
fossil glyptodonts to species, omitting the posibility of
G. arizonae based on age assignment. Additional interior
carapace osteoderms have the typical rosette pattern with
the central gure relatively small: TERA-27 (52.4 by 41.4
mm; 17.5 mm thick; central gure is 15.2 mm wide (29
percent of the diameter) and slightly depressed; TERA-29
(40.1 by 39.1 mm; 16.4 mm thick; central
gure is 16.7
Figure 2. Osteoderms of Glyptotherium cf. G. cylindricum from Térapa.
a: TERA-24; b: TERA-25; c: TERA-26. Scale is 10 mm.
Mead et al.
mm wide (42 percent of the diameter); TERA-30 (42.1 by
33.4 mm; 17.5 mm thick; central gure is 18.9 mm wide
(45 percent of the diameter); and TERA-50 (38.5 by 37.3
mm; 16.3 mm thick; central gure is 16.6 mm wide (43
percent of the diameter).
TERA-26 is a large osteoderm (53.9 by 48.5 mm) that
appears to be from the second row of osteoderms adjacent
to the border osteoderms along the caudal edge of the
carapace (Figure 2c).
TERA-51 is a 1.5m-long section of the carapace from
a single individual Glyptotherium (Figure 3). Some of the
osteoderms have the internal surface oriented up while
others have the external surface oriented up indicating that
sections of both the left and right side of the carapace are
preserved or that some were ipped over during burial. Four
osteoderms were measured: 35.0 by 41.8 mm (central gure
is 16.1 mm, or 38 percent of the diameter), 35.8 by 39.9 mm
(central gure is 15.9 mm, or 44 percent of the diameter),
40.9 by 37.3 mm, and 35.5 by 29.6 mm. The relative size of
the central gures from this carapace section indicates that
this specimen can also be referred to G. cylindricum.
The remains from La Botana include a small lateral
border fragment (NAU QSP-17886) and a mid-carapacial
osteoderm (NAU QSP-17887). The latter osteoderm is
more complete and has a maximum diameter of 48.4 mm
and a thickness of 20.1 mm. The central gure measures
19.8 mm. While the margin of the osteoderm is somewhat
broken, enough remains that we are con dent that our meas-
urements are good approximations. In any case, a slightly
larger maximum diameter would only serve to decrease the
ratio of the diameter of the central gure to the maximum
diameter of the osteoderm. As preserved, the central gure
is 40.9 percent of the osteoderm diameter, placing it well
within the range recorded for Glyptotherium cylindricum
and well below the minimum for G. mexicanus.
The 12 best preserved osteoderms from La Botana
(Tesopaco Locality 2) in the AMNH (59592, 59593 and
96369) gave an average maximum diameter of 51.6 mm
(46.8 – 58.9), an average length of the central gure of
20.5 mm (18.1 – 21.9), with the central gure averaging
39.8 percent (33.6 – 45.2) of the osteoderm diameter.
These osteoderms are also well within the range report-
ed for G. cylindricum and well below the minimum for
G. mexicanus.
We have examined the osteoderms in the AMNH from
Chinobampo and con rm their identity as Glyptotherium.
However, the dorsal surface is encrusted with a caliche-like
carbonate which obscures the sulci and makes measuring
the central gure inaccurate.
Superfamily Glyptodontoidea Gray, 1869
Family Pampatheriidae Paula Couto, 1954
Genus Pampatherium Gervais and Ameghino, 1880
Pampatherium cf. P. mexicanum Edmund, 1996
Fossil Material. Remains assigned to Pampatherium
include isolated imbricating and buckler osteoderms
Figure 3. A series of in situ, exposed osteoderms of Glyptotherium cf. G. cylindricum from a single section of carapace (TERA-51) from Térapa. Both
internal and external faces of osteoderms are showed. Scale is 100 mm.
Late Pleistocene Glyptodont and Pampathere from Sonora, Mexico 445
curs on TERA-20 and it is not depressed; the central gure
is attened and devoid of a keel or boss (Figure 4b). These
combined characters indicate that TERA-19 and 20 belong
to the genus Pampatherium and not Holmesina, although
both taxa are known from Mexico.
TERA-22 is relatively small (21.6 by 19.3 mm) with
a generally ovoid shape. It has only the slightest presence
of follicular pits along the margin, and may represent a
cephalic osteoderm. Although the specimens appear similar
to those described as P. mexicanum (Edmund, 1996) we
only tentatively ascribe the specimen to this species until
a more complete carapace or collection of osteoderms is
recovered from Térapa.
Remarks and identi cation. Pleistocene pampatheres are
represented by seven species in two genera: Holmesina and
Pampatherium. McKenna and Bell (1997) synonymized
these genera without comment; we retain the two genera
here. The osteoderms provide one mechanism for distin-
guishing these taxa (Edmund, 1996; Scillato-Yané et al.,
2005). Each osteoderm in the carapace bears a pattern
re ecting the ornamentation of its covering keratinous
osteoderm, which is distinctive for the genus and often for
the species (Edmund, 1985, 1987, 1996). The carapace of
all pampatheres has a mid-section consisting of three imbri-
cating bands of osteoderms. Anterior to these bands are the
pectoral buckler osteoderms and posterior to the bands are
the pelvic buckler osteoderms. All of these are distinct in
both ornamentation and size from the carapace osteoderms
found in the dasypodid armadillos (Edmund, 1985).
Buckler osteoderms from Pampatherium are weakly
ornamented (Figure 4b). The marginal band may be absent
(typical of the Mexican population) or may consist of a
narrow band of follicular pits on the posterior and lateral
margins; the marginal band is not signi cantly depressed
below the submarginal band (Edmund, 1996). The central
portion of the buckler osteoderms in Pampatherium is broad
and low with no boss or raised keel (Edmund, 1996). In
contrast to those of Pampatherium and those recovered from
Térapa, Holmesina buckler osteoderms have a distinct, al-
most continuous depressed margin, one with a submarginal
band that is a clearly de ned rectangle. The central region
typically is raised, often with a keeled boss (Edmund 1985,
1987, 1996; Scillato-Yané et al., 2005).
While three species of Pampatherium have been
described, only P. mexicanum is present in North America
(Edmund, 1996). Although the Térapa specimens appear
to match the holotype for that species, we take a conserva-
tive approach here and only tentatively assign our fossils
to species. The recovery of additional osteoderms or other
skeletal elements is needed to permit a more de nitive
identi cation.
TERA-18 is the anterior half of either an imbricating
osteoderm, or the anterior-most osteoderm of the pelvic
buckler (Figure 4a). It preserves the inclined surface over
which the osteoderm in front of it overlaps. The anterior-
most edge of TERA-18 has been broken so that the edge
is 5.3 mm in thickness. The osteoderm would match either
the C or D osteoderm of Edmund (1985).
TERA-20 is a complete buckler osteoderm that meas-
ures 42.5 mm long by 25.4 mm wide at the anterior end and
29.1 mm wide at the posterior end, and 8.4 mm in maximum
thickness (Figure 4b). TERA-20 is somewhat unusual in that
the osteoderm is wider at the posterior end; most buckler
osteoderms are either rectangular or slightly narrower at
the anterior end. TERA-19 is the anterior half of a buckler
osteoderm 24.6 mm wide and 7.2 mm in maximum thick-
ness (Figure 4c). Both buckler osteoderms are rectangular in
shape, lack the submarginal band and appear to have come
from the pelvic buckler. Only a slight follicular pit band oc-
Figure 4. Osteoderms of Pampatherium cf. P. mexicanum from Térapa. a:
TERA-18; b: TERA-20; c: TERA-19. Scale is 10 mm.
Mead et al.
Late Pleistocene Rancholabrean-age deposits are
common in Arizona and New Mexico, yet in adjacent north-
western Mexico (Sonora and Chihuahua) the published ac-
counts of such faunas are extremely rare. The few analyzed
Rancholabrean deposits and their faunas in Sonora either
date to the late Wisconsinan Glaciation (~< 80,000 years;
Arroyo-Cabrales et al., 2002) or possibly to the preceding
Sangamon interglacial (Van Devender et al., 1985). The
deposits at Térapa represent the most extensively studied
RLB deposits in Sonora, yet they may be of a different
radiometric age than the few other described faunas (Mead
et al., 2006). Until now, Glyptotherium and Pampatherium
dating to the RLB have not been reported from Sonora.
Miller and Carranza-Castañeda (2001) stated that the
understanding of the fossil fauna of Mexico has been greatly
enhanced through the investigations in central Mexico. As
was clearly stated by Arroyo-Cabrales et al. (2002), the fos-
sil history of northern Mexico is nearly void of information.
Figure 1 shows the known distributions of Glyptotherium
and Pampatherium. The presence of these taxa at Térapa
represents the rst published accounts of these species from
Sonora and greatly extends their known distributions during
the RLB into northwestern Mexico.
Glyptotherium of RLB age is found in central, eastern,
and Gulf Coastal Plain Texas and southeastern USA (pre-
dominantly Florida; Gillette and Ray, 1981). In Mexico,
Glyptotherium of RLB age is recorded from southeast-
ern Ciudad Delicias, Chihuahua (Silva-Bárcenas, 1969),
Cedazo, Aguascalientes (Mooser and Dalquest, 1975),
Ameca, Jalisco (Brown, 1912), and localities farther south
(McDonald, 2002; Figure 1). The Térapa and other Sonoran
localities rmly place Glyptotherium during the RLB at least
425 km farther west and 1,150 km farther north than previ-
ously recorded. Formerly, the farthest north occurrence of
Pampatherium during the RLB was in Jalisco (McDonald,
2002; Figure 1).
Environmental Setting
Térapa is situated today at the northern extent of the
subtropical thornscrub biotic community of the Neotropical
Realm (classi cation of Brown et al., 1998). More precisely,
the local vegetation today is part of the Foothills Thornscrub
– a transition between the Sonoran Desertscrub and the
Tropical Deciduous Forest (which occurs in the foothills of
the Sierra Madre Occidental within 250 km of the Arizona
border). Summer rains and protection from deep winter frost
are essential for tropical biota (Martin and Yetman, 2000).
Today the northern limits of the Neotropics are in central
Sonora, with a relatively abrupt transition between 28° and
32° N latitude (Van Devender et al., 2000). Tropicality in-
creases from sea level inland into the foothills of the Sierra
Madre Occidental. The northern limit of the Neotropics is
not along the coast but inland where it approaches 28° 30’N.
The Foothills Thornscrub reaches farther north to within
about 100 km of the Arizona border in the Moctezuma and
Bavispe drainages (Van Devender et al., 1994). Térapa
is on a tributary of the Río Yaqui at 29º 41’ N (Figure 1).
Tropical species reach their northern limits by being effec-
tively ‘squeezed’ between the cold temperatures of higher
latitudes and the inadequate summer moisture found at
lower elevations (Martin et al., 1998; Martin and Yetman,
2000). It is this ‘edge-effect’ that shifted north and south
or up and down in elevation as climate, particularly rainfall
and temperatures, cycled through glacial and interglacial
The recovered sediments, ostracodes, mollusks, and
vertebrates indicate that during the RLB local habitats at
Térapa included a slow moving stream, ponded water,
marsh, and submerged to emergent grasslands (Mead
et al., 2006). These authors inferred from the size of
the present Río Moctezuma valley that, during the late
Pleistocene, the setting permitted a well-developed riparian
corridor with tropical habitats that extended 350 km from
the coastal environments of the Gulf of California to the
interior location at Térapa. While the current imprecise
age assignment does not allow us to place the fauna from
Térapa within a particular Marine Isotope Stage, the fauna
which includes a crocodilian, capybaras, and most of the
recovered birds clearly indicate the presence of a subtropical
habitat farther north of its current boundary. A more precise
chronological analysis of the deposit is being conducted.
A precise chronology and environmental setting for
each of the three Río Mayo/Rio Yaqui localities of RLB
age is not yet available. However, tropical environments
currently extend up the drainage from the coast today, and
likely would have also done so during some or most climate
regimes during the Pleistocene. The Tropical Deciduous
Forest reaches about 1,000 m altitude within the drainage
(see Martin et al., 1998). We speculate that at least low
elevations along larger drainages, and the region of the
coast farther north of the Río Mayo, would have harbored
a robust tropical habitat during suitable Pleistocene climatic
regimes. What is not understood at present is whether or
not the required climate for the extension of tropical ora
and fauna to more northerly and /or more interior regions
occurred during a glacial or interglacial regime. Continued
detailed analysis of the Térapa locality, and our studies of
additional unpublished localities in Sonora, may hold the
answer to this and other questions.
Habitat Requirements
The habitat requirements for the extinct Glyptotherium
and Pampatherium are not fully known. As with the living
armadillos, the naked carapace on glytodonts and pam-
Late Pleistocene Glyptodont and Pampathere from Sonora, Mexico 447
patheres results in a high thermal conductance (McNab,
1978). The result is a smaller differential between body
temperature and the environment. Consequently, armadil-
los, and presumably glyptodonts and pamapatheres, despite
their larger size and improved body-mass to surface-area
ratio, would show a greater demand to increase metabolism
in order to maintain body temperature in response to small
changes in the ambient temperature. While Glyptotherium
fossils are known from farther north of Térapa into the
USA during the RLB, they are restricted to areas along
the Gulf of Mexico in the eastern portion of the continent.
Associated faunal elements in these regions imply a tropical
or at least subtropical habitat. It is also not yet determined
whether Glyptotherium and Pampatherium were tropical
obligates. This seems doubtful given the more northern
range of Glyptotherium. However, given the restricted
southern distribution of Pampatherium in North America in
comparison to Holmesina, and given that the other known
species of the genus are restricted to the tropics, it appears
more likely that Pampatherium was an obligate inhabitant
of tropical conditions.
We speculate that glyptodonts and pampatheres
lived in a habitat with abundant grass, and were grazers.
Webb (1978) included the Glyptotherium as one of nine
genera of savanna grazers that participated in the GABI.
In contrast, Gillette and Ray (1981) suggested that they
were likely “aquatic grazers” along with the capybaras.
Fariña (1995) questioned Gillette and Ray’s interpreta-
tion of Glyptotherium as having a preference for marshy,
lowland habitats based on a biomechanical analysis of
different South American genera of glyptodonts. The jaw
and dentition of Glyptotherium, as in other glyptodonts, is
well adapted for the processing of grasses. The jaw is deep
with extremely hypsodont, ever-growing teeth. The teeth
are among the most complex of any xenarthran teeth, being
trilobate with an arrangement of osteodentine in the center
to compensate for the lack of enamel, and the elongated and
massive zygomatic arch with a descending ange to orient
the masseter muscles to better grind abrasive vegetation such
as grasses (Ferigolo, 1985; Fariña, 1985, 1988).
In South America, all species of Pampatherium are
thought to be better adapted to extreme arid and semi-
arid environments than Holmesina (Scillato-Yané et al.,
2005). Based on a functional analysis of mastication in
Pampatherium, De Iuliis et al. (2000) concluded that among
the pampatheres, this genus was the most adept grazer of
resistant vegetation. Among the herbivorous cingulates, the
main differences in skull morphology re ected the degrees
of vegetation coarseness they were capable of processing.
Such differences probably re ected competitive exclusion
through niche partitioning within a shared biome or utiliza-
tion of different habitats (see Vizcaino et al., 1998). While
common in the Pampean region of Argentina, the range
of Pampatherium typum extended through Uruguay into
southern Brazil and west into Bolivia. Its widespread oc-
currence in this region is thought to re ect its adaptation to
a more arid environment (De Iuliis et al., 2000). The other
species, P. humboldtii, is known from the more tropical
portions of South America, particularly northern and eastern
Brazil. Types of vegetation in these regions varied through
time. Vegetation during interglacial intervals resembled that
of the modern ora while, during glacial times there was
increased aridity, with large portions of the Amazon Basin
becoming savanna and cerrado habitat. The distribution of
P. humboldtii overlapped that of Holmesina paulacoutoi
in this region. This distribution re ects the dynamics of
this changing habitat, and the two taxa may not have been
contemporaneous. They may have lived in the region alter-
natively, with Pampatherium being present during the times
when more arid savanna habitat predominated.
Although both Glyptotherium and Pampatherium
were recovered at Térapa along with other tropical elements,
there were also species in the fauna well adapted to a grass-
land/savanna habitat and more temperate climate, such as
Mammuthus, Equus, Camelops, and Bison. The ranges of
all these taxa also extend farther south of Térapa into central
Mexico so their presence at Térapa is not unexpected. The
distribution of Glyptotherium into the subtropical habitats
of the southeastern USA and its absence in Arizona or New
Mexico during the late Pleistocene RLB (Wisconsinan
Glaciation) would imply that this grazer required some sort
of tropical or subtropical element, including a permanent
water source in its habitat. The pampathere, Holmesina,
is known from eastern USA tropical habitats during the
Pleistocene, but never ventured west of the Texas coastal
region (Edmund, 1996). Pampatherium was not known
to have dispersed farther north than south-central Mexico
during the Pleistocene until it was found at Térapa. From
this distribution pattern, we conclude that Pampatherium
may have been a more tropical obligate than other South
American species within the genus and Glyptotherium.
The report here of Pampatherium and Glyptotherium
from RLB deposits in Sonora is unique and clearly illustrates
that much about the Pleistocene of northwestern Mexico is
only now beginning to be understood. More data is needed
to fully characterize the habitat, and to determine whether
the local plant community around Térapa during the RLB
was a grassland, a savanna, or a more closed community
with grass as an understory. Obviously the Neogene of
Sonora is in need of additional detailed eld and labora-
tory attention.
We thank Y. Petryszyn, P. Kresan, and C.V. Haynes
for their initial help with the project at Térapa. We also
appreciate assistance in the eld by E. Baez, A. Bair, T.
Bethard, V. Black, C. Bomberger, J. Bright, M.C. Carpenter,
J. Cruz, N.J. Czaplewski, G. Dean, F. and S. Duringer, P.
Gensler, M. Hollenshead, M. Imhof, R. Irmis, S. Jenkins,
C. Johnson, T. Joyal, A. Kelly, B. Long, C. McCracken, A.
Mead et al.
Mead, J. Meyers, G. Morgan, M. Palevich, W. Peachey, R.
Reppen, J. Toney, and G. Varhalmi. F. Tapia Grijalva and E.
Villalpando of Instituto Nacional de Antropología e Historia,
INAH Sonora, and J. Arroyo-Cabrales, Instituto Nacional
de Antropología e Historia, assisted with obtaining permits.
We thank H. Ruiz Durazo, S. Garcia Lopez, E. Maria Aruna
Moore, and many other people in the towns of Térapa,
Moctezuma, and El Llano for their continued support of our
project. We greatly appreciate the discussions and help from
N.J. Czaplewski, G. Morgan, P.S. Martin, E.H. Lindsay,
and C.J. Bell. We appreciate the continued discussions and
analyses on chronology, climate, and ostracodes from J.
Bright and D. Kaufman. We also appreciate the assistance
of Meng Jin, C. Norris, and S. K. Bell at the AMNH for
access to collections and to the records of Gentry’s eld
work which are contained in the Frick Archives. P. Jenkins
and R. Felger provided access to Gentry’s eld notes in the
Herbarium at the University of Arizona. We appreciate the
careful reviews of N.J. Czaplewski and T.R. Van Devender,
and the meticulous editing of C. White.
Arroyo-Cabrales, J., Polaco, O.J., Johnson, E., 2002, La mastofauna del cau-
ternario tardío en México, in Montellano-Ballesteros, M., Arroyo-
Cabrales, J. (eds.), Avances en los Estudios Paleomastozoológicos:
México, D. F., Instituto Nacional de Antropología e Historia, Serie
Arqueología, 103-123.
Aveleyra Arroyo de Anda, L., 1964, The primitive hunters, in Wauchope,
R. (ed.), Natural Environment and Early Cultures, Handbook of
Middle American Indians: Austin, Texas, University of Texas
Press, 1, 384-412.
Bell, C.J., Lundelius, E.L., Barnosky, A.D., Graham, R.W., Lindsay, E.H.,
Ruez, D.R., Semken, H.A., Webb, S.D., Zakrewski, R J., 2004,
The Blancan, Irvingtonian, and Rancholabrean mammal ages, in
Woodburne, M.O. (ed.), Late Cretaceous and Cenozoic Mammals
of North America: Columbia University Press, 232-314.
Brown, B., 1912, Brachyostracon, a new genus of glyptodonts from
Mexico: American Museum of Natural History Bulletin, 31,
Brown, D.E., Reichenbacher, F., Franson, S.E., 1998, A Classi cation of
North American Biotic Communities: Salt Lake City, University
of Utah Press, 141 p.
Carranza-Castañeda, O., Miller, W.E., 1987, Rediscovered type specimens
and other important published Pleistocene mammalian fossils
from central Mexico: Journal of Vertebrate Paleontology, 7,
Carranza-Castañeda, O., Miller, W.E., 2004, Late Tertiary terrestrial
mammals from central Mexico and their relationship to South
American immigrants: Revista Brasileira de Paleontologia,
7(2), 249-261.
Carranza-Castañeda, O., Roldán-Quintana, J., 2007, Mastofaunula de la
cuenca de Moctezuma, Cenozoico tardío de Sonora, México:
Revista Mexicana de Ciencias Geológicas, 24, 81-88.
Cope, E.D., 1889, The Edentata of North America: American Naturalist,
23, 657-664.
Czaplewski, N.J., 2004, A glyptodont (Mammalia, Xenarthra) from north-
ern Oklahoma: Oklahoma Geology Notes, 64, 4-9.
De Iuliis, G., Bargo, M.S., Vizcaíno, S.F., 2000, Variation in skull
morphology and mastication in the fossil giant armadillos
Pampatherium spp. and allied genera (Mammalia: Xenarthra:
Pampatheriidae) with comments on their systematics and
distribution: Journal of Vertebrate Paleontology, 20, 743-754.
Edmund, A.G., 1985, The armor of fossil giant armadillos (Pampatheriidae,
Xenarthra, Mammalia): Texas Memorial Museum, University of
Texas at Austin, Pearce-Sellards Series, 40, 1-20.
Edmund, A.G., 1987, Evolution of the genus Holmesina (Pampatheriidae,
Mammalia) in Florida, with remarks on taxonomy and distribu-
tion: Texas Memorial Museum, University of Texas at Austin,
Pearce-Sellards Series, 45, 1-20.
Edmund, A.G., 1996, A review of Pleistocene giant armadillos (Mammalia,
Xenarthra, Pampatheriidae), in Stewart, K.M., Seymour, K.L.
(eds.), Palaeoecology and Palaeoenvironments of Late Cenozoic
Mammals: Toronto, University of Toronto Press, 300-321.
Fariña, R.A., 1985, Some functional aspects of mastication in
Glyptodontidae (Mammalia): Fortschritte der Zoologie, 30,
Fariña, R.A., 1988, Observaciones adicionales sobre la biomecánica
masticatoria en Glyptodontidae: Boletín de la Sociedad Zoológica
del Uruguay, 4, 5-9.
Fariña, R.A., 1995, Limb bone strength and habits in large glyptodonts:
Lethaia, 28, 189-196.
Ferigolo, J., 1985, Evolutionary trends of the histological pattern in
the teeth of Edentata (Xenarthra): Archives Oral Biology, 30,
Flynn, J.J., Kowallis, B.J., Nuñez, C., Carranza Castañeda, O., Miller,
W.E., Swisher, III, C.C., Lindsay, E., 2005, Geochronology of
Hemphillian-Blancan aged strata, Guanajuato, Mexico, and im-
plications for timing of the Great American biotic interchange:
Journal of Geology, 113, 287-307.
Gentry, H.S., Hadley, D., 1995, Listening to my mind: Journal of the
Southwest, 37, 178-245.
Gervais, H., Ameghino, F., 1880, Les mammifères fossiles de l’Amérique
du Sud: Paris, F. Savy, 225 p
Gillette, D.D., Ray, C.E., 1981, Glyptodonts of North America: Smithsonian
Contributions to Paleobiology, 40, 1-255.
Gray, J.E., 1869, Catalogue of carnivorous, pachydermatous, and dentate
mammalia in the British Museum: London, British Museum
(Natural History), 398 p.
Hill, R.V., 2006, Comparative anatomy and histology of xenarthrans
osteoderms: Journal of Morphology, 267, 1441-1460.
Holmes, W.W., Simpson, G.G., 1931, Pleistocene exploration and fossil
edentates in Florida: Bulletin of the American Museum of Natural
History, 59, 383-418.
Illiger, C., 1811, Prodromus systematis mammalium et avium; additis
terminis zoographicis utriusque classis, eorumque versione ger-
manica: Berlin, C. Salfeld, 301 p.
Martin, P.S., Yetman, D.A., 2000, Introduction and Prospect. Secrets of
a tropical deciduous forest, in Robichaux, R.H., Yetman, D.A.
(eds.), The Tropical Deciduous Forest of Alamos. Biodiversity
of a Threatened Ecosystem in Mexico: Tucson, The University
of Arizona Press, 3-18.
Martin, P.S., Yetman, D., Fishbein, M., Jenkins, P., Van Devender, T.R.,
Wilson, R.K. (eds.), 1998, Gentry’s Río Mayo Plants, The tropi-
cal deciduous forest and environs of northwest Mexico: Tucson,
University of Arizona Press, 558 p.
McDonald, H.G., 2002, Fossil Xenarthra of México: a review, in Montellano-
Ballesteros, M., Arroyo-Cabrales, J. (eds.), Avances en los
Estudios Paleomastozoológicos: México, D. F., Instituto Nacional
de Antropología e Historia, Serie Arqueología, 227-248.
McKenna, M.C., Bell, S.K., 1997, Classi cation of Mammals above the
Species Level: New York, Columbia University Press, 631 p..
McNab, B.K., 1978, Energetics of arboreal folivores: physiological
problems and ecological consequences of feeding on an ubiquitous
food supply, in Montgomery, G.G. (ed.), The Ecology of Arboreal
Folivores: Washington, D.C., Smithsonian Institution Press,
Mead, J.I., Czaplewski, N.J., Agenbroad, L.D., 2005, Rancholabrean (Late
Pleistocene) mammals and localities of Arizona: Mesa Southwest
Museum Bulletin, 11, 139-180.
Mead, J.I., Baez, A., Swift, S.L., Carpenter, M.C., Hollenshead, M.,
Czaplewski, N.J., Steadman, D.W., Bright, J., Arroyo-Cabrales,
J., 2006, Tropical marsh and savanna environment during the
Late Pleistocene Glyptodont and Pampathere from Sonora, Mexico 449
Late Pleistocene in northeastern Sonora, México: Southwestern
Naturalist, 51(2), 226-239.
Mendoza-Durán, A., 2005, Armadillo, in Ceballos, G., Oliva, G. (eds.),
Los Mamíferos Silvestres de México: México, Comisión Nacional
para el Conocimiento y Uso de la Biodiversidad, Fondo de Cultura
Económica, 117-118.
Miller, W.E., Carranza Castañeda, O., 2001, Late Cenozoic mammals
from the basin of Central Mexico: Bollettino della Società
Paleontologica Italiana, 40(2), 235-242.
Mooser, O., Dalquest, W.W., 1975, Pleistocene mammals from
Aguascalientes, central Mexico: Journal of Mammalogy, 56,
Morgan, G.S., 2005, The Great American Biotic Interchange in Florida,
in Hulbert, R.C., Morgan, G.S., Baskin, J. A. (eds.), Cenozoic
Vertebrates of the Americas, Papers to Honor S. David Webb:
Florida Museum of Natural History Bulletin, 45(4), 271-311.
Morgan, G.S., Lucas, S.G., 2005, Pleistocene vertebrate faunas in New
Mexico from alluvial, fluvial, and lacustrine deposits: New
Mexico Museum of Natural History and Science Bulletin, 28,
Morgan, G.S., White, R.S., 2005, Miocene and Pliocene vertebrates from
Arizona: New Mexico Museum of Natural History and Science
Bulletin, 29, 115-136.
Osborn, H.F., 1903, ‘Glyptotherium texanum’, a new glyptodont, from the
Lower Pleistocene of Texas: Bulletin of the American Museum
of Natural History, 19(17), 491-494.
Paula Couto, C. de, 1954, Sobre um gliptodonte do Uruguai e um tatu fossil
do Brasil: Servicio Geologico y Mineralogico, Notas Preliminares
e Estudios, Rio de Janeiro, 80, 1-10.
Paz-Moreno, F., Demant, A., Cochemé, J-J, Dostal, J., Montigny, R.,
2003, The Quaternary Moctezuma volcanic eld: a tholeiitic to
alkali basaltic episode in the central Sonoran Basin and Range
Province, México: Geological Society of America, Special Paper,
Scillato-Yané, G.J., Carlini, A.A., Tonni, E.P., Noriega, J.I., 2005,
Paleobiogeography of the late Pleistocene pampatheres of
South America: Journal of South American Earth Sciences, 20,
Silva-Bárcenas, A., 1969, Localidades de vertebrados fósiles en la República
Mexicana: Universidad Nacional Autónoma de México, Instituto
de Geología, Paleontología Mexicana, 28, 1-34.
Van Devender, T.R., Rea, A.M., Smith, M.L., 1985, The Sangamon inter-
glacial vertebrate fauna from Rancho la Brisca, Sonora, Mexico:
Transactions of the San Diego Society of Natural History, 21,
Van Devender, T.R., Lowe, C.H., Lawler, H.E., 1994, Factors in uencing
the distribution of the Neotropical vine snake Oxybelis aeneus
in Arizona and Sonora, Mexico: Herpetological Natural History,
2, 27-44.
Van Devender, T.R., Sanders, A.C., Wilson, R.K., Meyer, S.A., 2000,
Vegetation, ora, and seasons of the Río Cuchujaqui, a tropi-
cal deciduous forest near Alamos, Sonora, in Robichaux, R.H.,
Yetman, D.A. (eds.), The Tropical Deciduous Forest of Alamos:
Biodiversity of a Threatened Ecosystem in Mexico. The University
of Arizona Press, Tucson, 36-101.
Vizcaino, S.F., De Iuliis, G., Bargo, M.S., 1998, Skull shape, masticatory
apparatus, and diet of Vassallia and Holmesina (Mammalia:
Xenarthra: Pampatheriidae): When anatomy constrains destiny:
Journal of Mammalian Evolution, 5(4) 291-322.
Webb, S.D., 1978, A history of savanna vertebrates in the New World. Part
II: South America and the Great Interchange: Annual Review of
Ecology and Systematics, 9, 393-426.
Webb, S.D., Rancy, A., 1996, Late Cenozoic evolution of the Neotropical
mammal fauna, in Jackson, J.B.C., Budd, A.F., Coates, A.G.
(eds.), Evolution and Environment in Tropical America: Chicago,
University of Chicago Press, 335-358.
White, R.S., Morgan, G.S., 2005, Arizona Blancan vertebrate faunas in
regional perspective: Mesa Southwest Museum Bulletin, 11,
Manuscript received: September 18, 2006
Corrected manuscript received: July 12, 2007
Manuscript accepted: August 10, 2007
... A Rancholabrean age is supported by the presence of Bison in the fauna [14]. The inferred paleohabitats include a slow-moving stream, ponded water, marsh, and savanna, or submerged to emergent grassland [14,15]. To this list, ref. [20] added riparian forest as a concurrent habitat type. ...
... In addition to the sloth, two other xenarthrans are present in the Térapa fauna: a glyptodont, Glyptotherium cylindricum, and a pampathere, Pampatherium cf. mexicanum [15]. The presence of these two taxa also supports the idea of a mild and moderate climate. ...
... It is associated with the pampathere, Pampatherium cf. mexicanum [15]. ...
Full-text available
While the North American mylodont sloth, Parmylodon harlani, has been identified in multiple localities in Mexico, most of these records are from the southern part of the country. Consequently, there is a large geographic gap between its distribution in Mexico and the more northern records of the species in the United States. The recovery of the remains of multiple individuals of Paramylodon harlani, as part of a late Pleistocene fauna in San Clemente de Térapa, Sonora, Mexico, partially fills this geographic gap and provides a broader understanding of the differences in the species’ ecology over a wide latitudinal range. A comparison of the paleoecology of the Térapa site with other sites with P. harlani in the fauna to the south and north provides valuable information on how regional topography and different plant communities impact the sloth’s distribution and underlying causes for its extinction.
... This latitudinal range of G. cylindricum was not synchronous, but instead shows a progressive retraction of geographical range during the Late Pleistocene with changing habitats during the last glacial (Fig. 1B, C). Interestingly, the latest records of G. cylindricum in Mexico at $21 ka (Flynn et al. 2005, Mead et al. 2007, Bravo-Cuevas et al. 2009, Ram ırez-Cruz & Montellano-Ballesteros 2014, Gillette et al. 2016) pre-date those from Guatemala and Venezuela at $16-9 ka and correlate with occurrences of G. cylindricum from southeastern North America that were previously identified as G. floridanum in the Late Pleistocene of Florida (Gillette & Ray 1981). ...
... Ma: Zurita et al. 2018). Fossils have been reported from the Late Pleistocene of the United States, Mexico, Costa Rica, Panama, Guatemala, Venezuela and Brazil (Gillette & Ray 1981, Laurito et al. 1993, Mead et al. 2007, Bravo-Cuevas et al. 2009, Ram ırez-Cruz 2014, Ram ırez-Cruz & Montellano-Ballesteros 2014, Gillette et al. 2016, together with a possible occurrence in the Pleistocene of Honduras and El Salvador (Webb & Perrigo 1984, Lucas 2008. In North America, G. cylindricum is known from Mexico in Aguascalientes, Chiapas, Hidalgo, Jalisco, the State of Mexico, Nuevo Le on, Oaxaca, Veracruz, Sonora, San Luis ...
... The geology of the site, described in detail by Mead et al. (2006), indicates a short-lived marshland environment with permanent ponds or streams, an interpretation supported by the presence of many water-loving fossil taxa including fishes, frogs, and aquatic reptiles. Fossil remains of large herbivores at the site have been used to infer the presence of grassland adjacent to the marshland (Mead et al., 2006(Mead et al., , 2007, although large mammals can travel long distances and are often poor indicators of vegetation. Isotopic studies performed by Nuńez et al. (2010) and avian faunal analysis by Steadman and Mead (2010) corroborate these interpretations, implying that the environment surrounding Térapa consisted of marshland, woodland and grassland habitats. ...
... Its Irvingtonian vertebrate fauna currently consists of over 80 taxa, including some potentially more southern taxa such as the giant anteater (Myrmecophaga tridactyla) and boa constrictor (Constrictor constrictor) (Shaw, 1981;Shaw and McDonald, 1987;Croxen et al., 2007). Previous reports on the fossil fauna of Térapa focused on mammals and birds (Mead et al., 2007;Nuńez et al., 2010;Steadman and Mead, 2010;Oswald and Steadman, 2011), whereas turtles have received comparatively little attention. Mead et al. (2006) noted that turtles dominated the reptilian remains at the site and reported the presence of "pond turtles." ...
Full-text available
The late Pleistocene of northern Mexico is relatively poorly understood, and represented by only a few fossil localities. One such locality is Térapa, located in east-central Sonora. The deposit dates to between 43,000 and 40,000 years old (Rancholabrean) and yields a rich fossil fauna of over 60 identified taxa, dominated by birds and large mammals. Geologic evidence at the site indicates a marshland with permanent sources of calm freshwater, which is supported by the presence of fossil remains of freshwater invertebrates, fishes, frogs, crocodilians and turtles. Previous studies have reported fossil turtles representing two families: Emydidae and Kinosternidae. Both of these families are represented in the extant fauna of Sonora. Here, we present the remains of two additional families of turtles from Térapa, Chelydridae and Trionychidae, both of which are absent today in the naturally-occurring fauna of Sonora. The extralimital presence of these families at Térapa indicates a significant biogeographical shift between the late Pleistocene and the present day. Previous studies have noted the similarly unusual discovery of crocodilians at Térapa, and proposed that its presence might be the result of dispersal into Sonora via coastal and riparian routes. We suggest a similar migration pattern might explain the presence of chelydrids and trionychids at the site, with the turtles dispersing into Sonora either from the north or from the south, and we discuss evidence for both scenarios.
... Recent publications have described Mammuthus and Cuvieronius (Mead et al., 2019), Glyptotherium cylindricum and Pampatherium cf. P. mexicanum (Mead et al., 2007), two shrews and six bats (Czaplewski et al., 2014), and 39 species of birds (Steadman and Mead, 2010;Oswald and Steadman, 2011). With Bison present throughout the stratigraphic profile, Térapa represents one of the few Rancholabrean North American Land Mammal Age (LMA) sites studied in detail in Sonora (Bell et al., 2004;Mead et al., 2006). ...
Full-text available
A paleontological deposit near San Clemente de Térapa represents one of the very few Rancholabrean North American Land Mammal Age sites within Sonora, Mexico. During that time, grasslands were common, and the climate included cooler and drier summers and wetter winters than currently experienced in northern Mexico. Here, we demonstrate restructuring in the mammalian community associated with environmental change over the past 40,000 years at Térapa. The fossil community has a similar number of carnivores and herbivores whereas the modern community consists mostly of carnivores. There was also a 97% decrease in mean body size (from 289 kg to 9 kg) because of the loss of megafauna. We further provide an updated review of ungulates and carnivores, recognizing two distinct morphotypes of Equus , including E . scotti and a slighter species; as well as Platygonus compressus ; Camelops hesternus ; Canis dirus ; and Lynx rufus; and the first regional records of Palaeolama mirifica , Procyon lotor , and Smilodon cf. S . fatalis . The Térapa mammals presented here provide a more comprehensive understanding of the faunal community restructuring that occurred in northern Mexico from the late Pleistocene to present day, indicating further potential biodiversity loss with continued warming and drying of the region.
... Cuevas et al., 2009), mientras que G. cylindricum presenta figuras centrales con una superficie que varía de plana a ligeramente convexa y son más grandes que las periféricas; G. mexicanum se distingue por tener figuras centrales más grandes que las periféricas(Gillette y Ray, 1981;Mead et al., 2007; Ramírez-Cruz y Montellano-Ballesteros, 2014), características ausentes en el material estudiado, al no contar con material más diagnóstico como los molares o el cráneo; se designan al ejemplar BUAPALZ-1090 tentativamente como G. floridanum, siendo el tercer registro de gliptodontes y el segundo registro de esta especie de gliptodonte para San Mateo Huexoyucán, Tlaxcala.Los ejemplares revisados corresponden a una asociación de mamíferos herbívoros pleistocénicos incluyendo Artiodáctilos (Bison antiquus, Camelops hesternus), proboscídeos (Cuvieronius hyodon, Mammuthus sp.), équidos (Equus conversidens, Equus mexicanus) y gliptodontes (Glyptotherium), los cuales corresponden con una asociación de mamíferos herbívoros rancholabreanos y concuerdan con los registros previos (Bonilla-Toscano, 2011; Ramírez-Cruz y Montellanos-Ballesteros, 2014; Sánchez-Salinas et al., 2016). La combinación de los siete taxa encontrados en este estudio se presenta para los sitios de Chapala-Zacoalco en Jalisco, Tequixquiac en el Estado de México y Valsequillo, Puebla(Ceballos et al., 2010;Ferrusquía-Villafranca et al., 2010), siendo San Mateo Huexoyucán, la cuarta localidad en el país con este ensamble de megafauna (Figura 7). ...
Full-text available
The fossils from San Mateo Huexoyucan, Tlaxcala, Mexico are formally described in this work. The specimens collected since 2011 include cranial and postcranial ele ments of Pleistocene Megafauna. The iden tification of the elements allows to postulate that they correspond to six previously reported species for the study area (Bison antiquus, Camelops hesternus, Cuvieronius hyodon, Equus conversidens, E. mexicanus and Mammuthus sp.), high lighting the presence of fossil material that corresponds to a juvenile individual of pro boscideans (Mammuthus sp.) and glyptodonts (cf. Glyptotherium floridanum).
... About 20 fossil sub-localities comprise the T erapa local fauna in an area of approximately 1 by 2 km. To date the following taxa or analyses have been described: crocodilian (Mead et al., 2006), birds (Steadman and Mead, 2010;Oswald and Steadman, 2011), shrews and bats (Czaplewski et al., 2014), glyptodont and pampathere (Mead et al., 2007), ostracodes and isotopes (Nunez et al., 2010;Bright et al., 2016), dire wolf (Hodnett et al., 2009), and a preliminary description of horse and bison (Carranza-Castañeda and Rold an-Quintana, 2007). Ungulates (including detailed bison description), rodents, additional carnivores, mollusks, anurans, a caudate, and squamates are presently being described. ...
What is currently known about México paleontology and specifically the proboscideans has centered in the central and southern states, with much of the north largely unknown. Here we report on Cuvieronius (Gomphotheriidae) and Mammuthus (Elephantidae) recovered from Térapa, a Late Pleistocene site in east-central Sonora. The local fauna reflects a badlands environment along the Río Moctezuma, 183 km (114 mi) south of the Arizona border. The recovery of Bison places the locality within the Rancholabrean Land Mammal Age. Chronological analyses confirm that impounding basalt and fossiliferous sediments were deposited 43,000 to 40,000 years ago (MIS 3). Cuvieronius and Mammuthus are found throughout the stratigraphic profile. A review of Late Pleistocene collections indicates that Mammuthus, Cuvieronius, and one location of Mammut are known from Sonora. The Late Pleistocene along the Térapa river valley is reconstructed as cooler, with a more equable, less seasonal environment than today. The corridor was wetter, more tropical and included a riparian forest, ponding water, marsh, and savanna grassland. The area west of Térapa in western Sonora had a cooler summer climate, more winter rains and less summer rains. Woodlands and shrub communities occupied the upper bajadas and rocky hills, areas possibly where Mammut ranged more commonly. Valleys contained more grasslands than they do today. The environments and climates of valleys permitted Cynomys, Mammuthus, and Cuvieronius to exist over most of western Sonora where they are extinct today.
Full-text available
We describe a new species of capybara from late Pleistocene deposits (Rancholabrean NALMA) in northern San Diego County, California, USA which tentatively dates to Marine Isotope Stage (MIS) 5 interglacial (~130 ka to 80 ka). The specimen represents a new species of Hydrochoerus based on morphological characters of the upper incisor (I1) and the upper (maxillary) third molar (M3). Hydrochoerus hesperotiganites sp. nov. differs from other described species of Hydrochoerus in its larger size, wider skull roof, more robust zygomatic process of the maxilla and descending zygomatic process of the lacrimal and in details of the otic region. The new species is the only confirmed record of fossil Hydrochoerus in North America and is the northwestern-most record of any capybara in North America. All previous records of fossil capybara from North America represent one of two extinct genera, Neochoerus or Phugatherium. Northward dispersal of capybaras from central and southern México probably occurred along the coasts of Sinaloa and Sonora, entering the north or northeast flowing drainages which enter the Gulf of California, then further north into the San Simon drainage to the Gila River and ultimately intothe Colorado River, or directly northward along the coast of Sonora to the mouth of the Colorado River.
From the time that the first xenarthrans appeared as early armadillos in the Early Paleocene Itaborai, the group diversified into strange and wonderful forms. Besides the Dasypodidae, a group called the Glyptodontidae arose and diversified; some were the size (and shape) of a Volkswagen bug and were harmless grazers. They were very common on the grassy savannas of South America. Also, the sloth lineage appeared with the last species reaching the greatest size of any southern mammal. Megatherium americanum became one of the largest mammals known in South America, equivalent in size to an elephant. Finally a short history of the little-known anteaters is presented. A discussion of the possible but unconfirmed origins of the xenarthra is suggested, and the group is presented as one of the most ancient lineages of modern mammals and native South Americans.
New scute remains of Cingulata recovered from the Upper Cenozoic of Buenos Aires de Palmares locality are described. The small osteoderm founds confirms the presence of the Pachyarmatherium genus and its North American species at southern Central American. Besides, its association with the giant scutes of Glyptotherium arizonae permits to deduce a Late Blancan to Early Irvingtonian age.
It is described the second fossil record of the family Camelidae and the first of the genus Palaeolama for Costa Rica, which was found together with Glyptotherium plates. This association provides new data about the Great American Biotic Interchange. The material fossil assigned to Camelidae consists of a rear left metapodial. Based on previous studies of fossils from nearby areas these new records are assigned an Early Irvigtonian age.
Full-text available
Bones of 51 species of vertebrates including fish, amphibians, reptiles, birds, and mammals were recovered from a sedimentary deposit at Rancho la Brisca in north-central Sonora, Mexico. The fauna was preserved in a marshy cienega habitat with 49.0% of the species and 87.2% of the identified bones representing aquatic and semiaquatic animals. The most common animals in the fauna are Kinosternon sonoriense (Sonoran Mud Turtle) and Rana 'pipiens'-complex (Leopard Frog). The presence of Bison species, Mammuthus species, Equus cf. tau, and Camelops species places the fauna in the Rancholabrean Land Mammal Age. Bugo cf. kelloggi, B. mazatlanensis, Leptodactylus melanonotus, Pternohyla fodiens, and Masticophis cf. mentovarius are subtropical thornscrub animals that presently occur to the south and/or west of la Brisca. Bufo alvarius cf. Callisaurus draconoides and Sceloporus cf. clarkii are other animals that suggest a paleoclimate with warm winters and a well-developed summer monsoon. The fauna represents an interglacial environment subsequent to the appearance of Bison about 150 000 years ago in the Sangamon Interglacial and with a climate similar to that of the Late Holocene of the last 4000 years. The distribution of fish and mud turtles suggest past stream connections between the Gila River drainage in southeastern Arizona and the rivers in Sonora. In contrast, Pseudemys scripta (Yaqui Slider) apparently never entered Arizona, although it reaches north-central Sonora today. -from Authors